This invention relates generally to hand-held tie tampers for compacting ballast gravel under the lower surfaces of ties of railroad tracks. More specifically, the invention relates to a tie tamper in which a handle to be grasped by the operator and a vibration motor for generating vibration to which a beater is fixed are connected by way of Neidhart dampers and a link mechanism, and balance weights are provided at the pin joint between links in the link mechanism thereby to increase the effect of reducing or suppressing the transmission of vibration from the vibration generating motor to the handle.
A tie tamper known heretofore comprises, essentially, a motor adapted to generate vibration (hereinafter referred to as a "vibromotor"), a beater rigidly fixed to the vibromotor and being vibrated thereby, the beater being thrust into railroad ballast gravel during operation, a handle, and a leaf spring and a support spring joining the handle to the vibromotor, as will be described more fully hereinafter.
The leaf spring is intended to reduce the transmission of vibration from the vibromotor to the handle. However, since the leaf spring has a linear characteristic, the same vibration reducing effect cannot be sustained when the work condition changes. That is, the work condition when the beater is vibrating freely in the air is different from that when it is vibrating after being thrust into ballast gravel. When the beater is thrust deeply into ballast gravel and is constrained, the work condition also changes. Thus, depending on the work condition, intense vibration or impact-like vibration is transmitted to the hands of an operator using the above mentioned tie tamper of known type, as will be described more fully in conjunction with a drawing.